Analysis of the heat transfer time in rubber aggregate concrete as a function of humidity percentage at very high temperature

Abstract

This study deals with the analysis of the thermal behavior of concrete based on rubber aggregates. The objective is to study the effect of humidity and the role of rubber aggregates on the thermal behavior of concrete, especially the time of heat transmission within the material at very high temperatures such as during a fire. The study is carried out according to two approaches, an experimental approach that allows us to determine the characteristics of concrete in the initial state (density, heat capacity and thermal conductivity), and a numerical approach to characterize the behavior of recycled concrete at very high temperature and determine the time of heat transmission. The results obtained showed that recycled concrete based on rubber aggregates has several advantages when the concrete is exposed to high temperatures such as during a fire. Indeed, with a humidity of 1.5% and a percentage of 10%, 20% and 30% of rubber aggregates, we can gain 23.8%, 41% and 63.7% on the time of heat transmission compared to the reference concrete, and with a humidity of 3% and a percentage of 10%, 20% and 30% of rubber aggregates we can gain 22. 5%, 40% and 63.3% compared to the reference concrete, and with a humidity of 10% and a percentage of 10%, 20% and 30% of rubber aggregates we can gain 23.6%, 40.7% and 63.8% still compared to the reference concrete. However, a high percentage of moisture in the concrete generates an increase in pressure and favors the increase of the thermal gradient due to the energy necessary for the vaporization of the liquid water, and according to the literature it is recommended not to exceed a percentage of moisture 3% in order to avoid the thermal stability as well as the spalling of concrete.